• for the good of sy, in behalf of sy, in favour of sy, on behalf of sy, on sy's behalf
• for the sake of the cause
• for one's own good, in one's own interest
• for the sake of the cause
• to act on sy's behalf, to act on sy's behoof, to take sy's interest
• in the interest of, in the interest of sy
• in the interest of, in the interest of sg
• to speak for sy, to speak up for sy
• to put in a word for sy
• to speak in support of sg
• for this express purpose
• to plead sy's cause with sy
• to give sy one's good word, to put in a word for sy
• to plead sy's cause with sy